Liberty Lake
Annual water quality monitoring occurs on Liberty Lake by personnel from the Washington State University Department of Natural Resource Sciences under contract with the Liberty Lake Sewer and Water District. The primary purpose of the Liberty Lake monitoring is to provide information to help the community understand lake water quality status, assess trends in lake water quality, and to guide the community and the district in decisions regarding lake and watershed management. Sampling occurs biweekly throughout the growing season (early spring to late fall) and assesses dissolved oxygen, temperature, conductivity, alkalinity, pH, clarity, algae, zooplankton, and nutrients (phosphorus and nitrogen). In addition to the lake monitoring, sampling of the inlet streams (Clarke, Stokke, Kamiakin, and West fork of Liberty Creek) also occurs biweekly by personnel from WSU and the LLSWD.
BiJay Adams, General Manager and past Lake Protection Manager for the Liberty Lake Sewer and Water District, established real time telemetry monitoring stations for Liberty Lake and Creek. Liberty Lake and Creek stilling wells are equipped with pressure transmitters that captures both water temperature and pressure and provides a signal proportional to the magnitude of these parameters. The data are transmitted via radio waves and linked to the world wide web via a radio telemetry modem.
A 6 inch ductile iron stilling well has been installed on Liberty Lake at a private homeowners association park. The purpose for the installation of this site is to monitor the continuous level of Liberty Lake and maintain the level of the lake at or below the 1951 adjudicated level (2049.51 feet above sea level). This stilling well offers real time data valuable for calculating lake volume, evaporation, and residence time, plotting and calculating the rise and fall of the lake level, and pin pointing runoff and storm events. Ongoing monitoring will ensure quality data useful in calculating hydrologic and nutrient budgets while maintaining and establishing baselines and trends. Unlike the remote area of Liberty Creek, this site has direct power through cooperation of Avista Utilities and the homeowners association. Two existing staff gages are on Liberty Lake to correlate to the real time data collected by the telemetry station and to ensure the accuracy of the data being reported.
Liberty Creek
Liberty Creek is the main tributary to Liberty Lake, where it drains approximately 10 square miles of mountainous watershed area above the lake (Montgomery Consulting, 1990). The County Park encompasses approximately 3500 acres of this mountainous watershed. Through most of its length, the creek is a swift stream of very cold, high quality, nutrient poor water, and generally exceeds Washington State Water Quality Standards for Class AA (“extraordinary”) waters in all physical and chemical characteristics (Water Quality Criteria, Washington State Department of Ecology, 1982).
At the south end of the lake is a seasonal 155-acre wetland. In 1934, the Bureau of Reclamation constructed a bifurcation in Liberty Creek to assist and divert stream flow around the wetland and to stop annual flooding of the wetland from runoff. In conjunction with the bifurcation, the Bureau also constructed a wetland-lake dike to assist in draining and improving the marshland for agricultural and animal farming activities. Later in 1950, channel modifications were conducted in which the stream flowed in a manmade diked channel along the east edge of the wetland. In 1977, a diversion structure was installed on the creek at the bifurcation, and channel improvements and dike construction followed in 1979 (Kennedy, 1986).
A 6 inch PVC stilling well has been installed on Liberty Creek above the bifurcation and channel modifications. The purpose for the installation of this site is to monitor the continuous flow of Liberty Creek into the wetland and lake. This stilling well will offer real time data valuable for calculating discharge, plotting the stream hydrograph, and pin pointing runoff and storm events critical for nutrient sampling and loading. Ongoing monitoring will ensure quality data useful in calculating hydrologic and nutrient budgets while maintaining and establishing baselines and trends. A rating curve has been established for discharge at the site.
